An example of a conventional one-way clutch, as shown in FIGS. 1 and 2, uses a plurality of sprags S inserted, one in contact with another, between concentric outer and inner rings 1 and 2, respectively, one of which rotatably drives the other. An annular garter spring 5 is fitted in a groove 4 provided on each side of the sprag. An annular side plate 6 is disposed on each side of the sprag. A stopper ring 20, fitted in an annular groove formed in the internal surface of the outer ring 1, is provided on the outside of each side plate 6.
Another example of a conventional one-way clutch, as shown in FIGS. 3 and 4, uses a plurality of sprags S' inserted at intervals between the outer ring 1 and the inner ring 2. An annular garter spring 5 is fitted in each edge groove 4. A retainer 8, made of steel sheet punched with a sprag inserting hole 7, is used to keep the sprags spaced at given intervals.
The former type, shown in FIGS. 1 and 2, is assembled by inserting the individual sprags S one by one. This assembling work is not only laborious and inefficient, but is also likely to cause misfitting. The adjacent sprags interfere with each other to prevent smooth motion, with the points of contact moving in opposite directions as indicated by the arrows. Governed by the circumferential length of the outer and inner rings, the number of sprags cannot be decreased according to the required torque. Provision of the groove 4 to insert the garter spring 5 on each side of the sprag reduces the area of contact between the side of the sprag and the annular side plate 6. Consequently, if the sprag gives a localized axial push to the annular side plate 6, localized abrasive wear is likely to occur. Especially if the annular side plate 6 warps outward, the localized abrasive wear increases, greatly preventing the smooth motion of the sprags.
In the latter clutch, shown in FIGS. 3 and 4, the sprags S' are spaced away from each other by means of the retainer 8, so that the space between the adjacent sprags is not effectively used and the number of sprags insertable between the rings is limited, thereby limiting the ability for torque transfer. The revolving sprag sometimes interferes with, and thereby damages, the retainer 8. Owing to the inertia of circumferential motion, etc., the retainer 8 sometimes prevents the sprag from revolving, thereby making it impossible to engage or disengage the clutch. Because of the need to maintain high strength, the retainer 8 is usually made by blanking relatively heavy steel sheet. This, however, involves low material-to-product yield and high production cost. Besides, the increased retainer weight increases the inertia of motion, producing adverse effect on clutch performance. Blanking thinner steel sheet develops burrs which prevent the sprag from moving smoothly along and around the axis, and cause the sprag inserting hole 7 to wear easily.
This invention eliminates the aforementioned short-comings of conventional one-way clutches.
In the improved one-way clutch of the present invention, a plurality of sprags disposed in an annular array are positioned within an annular space between concentric inner and outer rings. Each sprag has a groove formed therein substantially midway between the ends thereof, which groove opens outwardly of the sprag in a direction which extends radially relative to the inner and outer rings, the groove being effectively defined by a plane which is substantially perpendicular to the rotational axis of the clutch. A garter spring is fitted within the grooves defined by the plurality of sprags. An annular retainer is also disposed within the annular spece for holding and positionally confining the sprags. The annular retainer has axially extending parts which are circularly joined together, whereby the axially extending parts positionally hold the sprags.
In a preferred embodiment of the invention, the clutch has the retainer positioned directly adjacent the inner ring so that the surrounding garter spring urges the sprags into engagement with the axially extending parts of the retainer, whereby the retainer, sprags and garter spring can be fully assembled as a unit prior to insertion of same between the inner and outer rings.
Other objects and purposes of the invention will be apparent from the following detailed description.